Piping structure and process and pipe construction method

Abstract

A piping structure and a process, with which it is possible to form an opening in a pipe while preventing shavings produced from cutting from entering the pipe. A process for forming an opening in a pipe, including: a step of enclosing the pipe with a case divided in a circumferential direction R of the pipe; a skin formation step of cutting an outer surface of the pipe with a cutting tool arranged in the case, thereby forming a bottomed groove, which is formed as a skin, on the pipe; a suction step of sucking shavings produced from cutting, together with a gas in the case in order to remove the shavings; and breaking the skin to form the opening after performing the skin formation step and the suction step.

The invention claimed is: 
     
       1. A process for forming an opening in a pipe, comprising:
 a step of enclosing a portion of the pipe with a case, wherein a cutter having a milling-shaped tool as a cutting tool is attached to the case; 
 a skin formation step of cutting an outer surface of the pipe with the cutting tool arranged in the case, thereby forming a groove on the pipe, the groove having a bottom that is formed as a skin; 
 a removal step of removing shavings produced from the cutting; and 
 a step of thrusting through the skin to form the opening, after performing the skin formation step and the removal step. 
 
     
     
       2. The process according to  claim 1 , wherein the skin formation step is performed by revolving the cutting tool in a circumferential direction of the pipe together with the case while rotating the milling-shaped cutting tool about a central axis of the tool, thereby forming the groove having the bottom, the groove being elongated in the circumferential direction. 
     
     
       3. The process according to  claim 2 , further comprising an insertion step of inserting a gate valve body into the pipe through the opening. 
     
     
       4. The process according to  claim 1 , further comprising a step of forming a coating on a surface of the groove on the pipe after performing the skin formation step and the removal step and before the step of forming the opening. 
     
     
       5. The process according to  claim 1 , wherein the cutting tool is revolved in a circumferential direction of the pipe and moved in a pipe axial direction of the pipe while rotating the milling-shaped cutting tool about a central axis of the tool, thereby forming the bottomed groove in a loop shape, thus performing the skin formation step. 
     
     
       6. The process according to  claim 5 , wherein:
 in the step of forming the opening, a loop-shaped blade, which coincides with the loop-shaped bottomed groove, is used to thrust through the skin, thereby forming the opening to be a branch port in the pipe; and 
 the process further comprises a step of removing the loop-shaped blade. 
 
     
     
       7. A process for forming an opening in a pipe, comprising:
 a step of attaching a rotating unit around the pipe, the rotating unit being rotatable in a circumferential direction of the pipe, wherein a cutter having a milling-shaped cutting tool is attached to the rotating unit; 
 a skin formation step of revolving the cutting tool in the circumferential direction of the pipe together with the rotating unit while rotating the milling-shaped cutting tool about a central axis of the tool, thereby cutting an outer surface of the pipe to form a groove on the pipe, the groove being elongated in the circumferential direction and having a bottom that is formed as a skin; 
 a removal step of removing shavings produced from the cutting; and 
 a step of thrusting through the skin to form the opening, after performing the skin formation step and the removal step. 
 
     
     
       8. The process according to  claim 7 , wherein:
 the rotating unit includes a case that is divided in the circumferential direction of the pipe; 
 in the attachment step, a portion of the pipe is enclosed with the case, the process further comprising: 
 an assembly step of assembling, instead of the tool, a flat plate-shaped gate valve body to the case before the step of forming the opening, the gate valve body being used for thrusting through the skin; and 
 an insertion step of inserting the gate valve body into the pipe through the opening in the step of forming the opening. 
 
     
     
       9. The process according to  claim 8 , wherein the gate valve body includes:
 a circular-shaped valve main body that enters an inside of the pipe; a blade that is provided on a distal end side of the valve main body for breaking the skin to form the opening; and 
 a seal portion that is provided on a proximal end side, which is opposite to the distal end side, and contacts a portion of the pipe around the opening to shut the opening, wherein: 
 the blade of the gate valve body thrusts through the skin, thus performing the step of forming the opening; and 
 the valve main body of the gate valve body enters the pipe, and the seal portion contacts the portion of the pipe around the opening and the distal end side of the valve main body contacts an inner periphery surface of the pipe, thus performing the insertion step. 
 
     
     
       10. The process according to  claim 9 , wherein:
 the groove extends in the circumferential direction R of the pipe; 
 the skin is formed so that a thickness of a central portion of the skin in a pipe axial direction is thinner than opposite side portions of the skin in the pipe axial direction; and 
 the blade breaks the thin central portion, thereby performing the step of forming the opening. 
 
     
     
       11. The process according to  claim 7 , further comprising:
 a step of removing the rotating unit and the cutter; 
 an assembly step of assembling a case to the pipe so that the case encloses the bottomed groove of the pipe, the case accommodating therein a flat plate-shaped gate valve body that thrusts through the skin, the assembly step performed prior to the step of forming the opening; and 
 an insertion step of inserting the gate valve body into the pipe through the opening in the step of forming the opening. 
 
     
     
       12. The process according to  claim 7 , further comprising a step of forming a coating on a surface of the groove on the pipe after performing the skin formation step and the removal step and before the step of forming the opening. 
     
     
       13. A pipe construction process for obtaining a piping structure, the piping structure including a gate valve body assembled into a pipe, the piping structure comprising:
 a pipe that defines a groove extending in a circumferential direction, the groove having a bottom that is formed as a skin; 
 a case that encloses a portion of the pipe including the groove having the bottom; 
 a gate valve body that is arranged in the case; and 
 a valve rod that brings the gate valve body closer toward the groove and further moves the gate valve body so as to thrust through the skin of the bottom of the groove to form an opening, 
 wherein the gate valve body includes: 
 a circular-shaped valve main body that enters an inside of the pipe; 
 a blade that is provided on a distal end side of the valve main body for breaking the skin to form the opening; and 
 a seal portion that is provided on a proximal end side, which is opposite to the distal end side, and contacts a portion of the pipe around the opening to shut the opening, 
 the pipe construction process comprising: 
 a step of attaching a rotating unit around the pipe, the rotating unit being rotatable in the circumferential direction of the pipe, wherein a cutter having a milling-shaped cutting tool is attached to the rotating unit; 
 a skin formation step of revolving the cutting tool in a circumferential direction of the pipe together with the rotating unit while rotating the milling-shaped cutting tool about a central axis of the tool, thereby cutting an outer surface of the pipe to form the groove on the pipe, the groove being elongated in the circumferential direction and having the bottom that is formed as the skin; 
 a removal step of removing shavings produced from the cutting; 
 a step of removing the rotating unit and the cutter from the pipe; and 
 a step of attaching the case accommodating the gate valve body therein to the pipe so that the case encloses the portion of the pipe including the groove having the bottom. 
 
     
     
       14. The pipe construction process according to  claim 13 , wherein:
 the blade of the valve main body is made of metal; and 
 with the valve main body in a valve-closed state, the metal-made blade contacts an inner periphery surface of the pipe, and the seal portion contacts the portion of the pipe around the opening.